Inner tube assembly for dual conduit drill pipe

摘要

In a dual conduit drill pipe section having concentric inner and outer tubes, a plurality of centering lugs are provided which are disposed between the inner and outer tubes and include bearing surfaces which are adapted to reduce the friction and wear associated with the movement of the inner tube with respect to the outer tube. The inner tube is secured to the outer tube at one point along each pipe section by a heat meltable adhesive which bonds an anchor ring which is secured to the inner tube to a shoulder defined in the inner surface of the outer tube.